Interstitial brachytherapy apparatus and method for treatment of proliferative tissue diseases

ABSTRACT

An interstitial brachytherapy apparatus for delivering radioactive emissions to an internal body location includes a catheter body member having a proximal end and distal end, an inner spatial volume disposed proximate to the distal end of the catheter body member, an outer spatial volume defined by an expandable surface element disposed proximate to the distal end of the body member in a surrounding relation to the inner spatial volume, and a radiation source disposed in the inner spatial volume.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/900,021, filed Jul. 24, 1997, now U.S. Pat. No. 5,913,813the contents of which are specifically incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention relates generally to apparatus for use in treatingproliferative tissue disorders, and more particularly to an apparatusfor the treatment of such disorders in the body by the application ofradiation.

Malignant tumors are often treated by surgical resection of the tumor toremove as much of the tumor as possible. Infiltration of the tumor cellsinto normal tissue surrounding the tumor, however, can limit thetherapeutic value of surgical resection because the infiltration can bedifficult or impossible to treat surgically. Radiation therapy can beused to supplement surgical resection by targeting the residual tumormargin after resection, with the goal of reducing its size orstabilizing it. Radiation therapy can be administered through one ofseveral methods, or a combination of methods, including external-beamradiation, stereotactic radiosurgery, and permanent or temporaryinterstitial brachytherapy. The term “brachytherapy,” as used herein,refers to radiation therapy delivered by a spatially confinedradioactive material inserted into the body at or near a tumor or otherproliferative tissue disease site. Owing to the proximity of theradiation source, brachytherapy offers the advantage of delivering amore localized dose to the target tissue region.

For example, brachytherapy is performed by implanting radiation sourcesdirectly into the tissue to be treated. Brachytherapy is mostappropriate where 1) malignant tumor regrowth occurs locally, within 2or 3 cm of the original boundary of the primary tumor site; 2) radiationtherapy is a proven treatment for controlling the growth of themalignant tumor; and 3) there is a radiation dose-response relationshipfor the malignant tumor, but the dose that can be given safely withconventional external beam radiotherapy is limited by the tolerance ornormal tissue. In brachytherapy, radiation doses are highest in closeproximity to the radiotherapeutic source, providing a high tumor dosewhile sparing surrounding normal tissue. Interstitial brachytherapy isuseful for treating malignant brain and breast tumors, among others.

Interstitial brachytherapy is traditionally carried out usingradioactive seeds such as ¹²⁵I seeds. These seeds, however, produceinhomogeneous dose distributions. In order to achieve a minimumprescribed dosage throughout a target region of tissue, high activityseeds must be used, resulting in very high doses being delivered in someregions in proximity to the seed or seeds which can cause radionecrosisin healthy tissue.

Williams U.S. Pat. No. 5,429,582, entitled “Tumor Treatment,” describesa method and apparatus for treating tissue surrounding a surgicallyexcised tumor with radioactive emissions to kill any cancer cells thatmay be present in the tissue surrounding the excised tumor. In order toimplement the radioactive emissions, Williams provides a catheter havingan inflatable balloon at its distal end that defines a distensiblereservoir. Following surgical removal of a tumor, the surgeon introducesthe balloon catheter into the surgically created pocket left followingremoval of the tumor. The balloon is then inflated by injecting a fluidhaving one or more radionuclides into the distensible reservoir via alumen in the catheter.

The apparatus described in Williams solves some of the problems foundwhen using radioactive seeds for interstitial brachytherapy, but leavessome problems unresolved. The absorbed dose rate at a target pointexterior to a radioactive source is inversely proportional to the squareof the distance between the radiation source and the target point. As aresult, where the radioactive source has sufficient activity to delivera prescribed dose, say 2 centimeters into the target tissue, the tissuedirectly adjacent the wall of the distensible reservoir, where thedistance to the radioactive source is very small, may still be overly“hot” to the point where healthy tissue necrosis may result. In general,the amount of radiation desired by the physician is a certain minimumamount that is delivered to a region up to about two centimeters awayfrom the wall of the excised tumor. It is desirable to keep theradiation that is delivered to the tissue in the target treatment regionwithin a narrow absorbed dose range to prevent over-exposure to tissueat or near the reservoir wall, while still delivering the minimumprescribed dose at the maximum prescribed distance from the reservoirwall.

There is still a need for an instrument which can be used to deliverradiation from a radioactive source to target tissue within the humanbody with a desired intensity and at a predetermined distance from theradiation source without over-exposure of body tissues disposed betweenthe radiation source and the target.

SUMMARY OF THE INVENTION

The present invention solves the problems described above by providingan interstitial brachytherapy apparatus for delivering radioactiveemissions to an internal body location. The apparatus includes acatheter body member having a proximal end and distal end, an innerspatial volume disposed proximate to the distal end of the catheter bodymember, an outer spatial volume defined by an expandable surface elementdisposed proximate to the distal end of the body member in a surroundingrelation to the inner spatial volume, and a radiation source disposed inthe inner spatial volume. The inner and outer spatial volumes areconfigured to provide an absorbed dose within a predetermined rangethroughout a target tissue. The target tissue is located between theouter spatial volume expandable surface and a minimum distance outwardfrom the outer spatial volume expandable surface. The predetermined doserange is defined as being between a minimum prescribed absorbed dose fordelivering therapeutic effects to tissue that may include cancer cells,and a maximum prescribed absorbed dose above which healthy tissuenecrosis may result.

In different embodiments, the inner spatial volume can be defined by adistensible polymeric wall containing radioactive source material whichcan be a fluid material, by a solid radioactive source, or by a regioncontaining a plurality of solid radioactive sources. The outer spatialvolume is defined by an expandable surface element that may be, forexample, an inflatable polymeric wall or an expandable cage. Theexpandable surface element can cause tissue to conform to its intendedshape, and preferably, the apparatus creates absorbed isodose profilesin the target tissue that are substantially similar in shape to theexpandable surface element in substantially three dimensions.

The invention also provides a method for treating a proliferating tissuedisease using interstitial brachytherapy at an internal body location.The method includes surgically creating access to the proliferatingtissue within a patient and surgically resecting at least a portion ofthe proliferating tissue to create a resection cavity within bodytissue. An interstitial brachytherapy apparatus for deliveringradioactive emissions as described above is then provided andintra-operatively placed into the resection cavity. After a prescribedabsorbed dose has been delivered to tissue surrounding the apparatus,the apparatus is removed. The radioactive source material may be placedinto the interstitial brachytherapy apparatus after the apparatus isplaced in the resection cavity, and may be removed before the apparatusis removed. The method has particular applications to brain and breastcancers.

DESCRIPTION OF THE DRAWINGS

The foregoing features, objects and advantages of the invention willbecome apparent to those skilled in the art from the following detaileddescription of a preferred embodiment, especially when considered inconjunction with the accompanying drawings in which:

FIG. 1 is a side view of an interstitial brachytherapy apparatus of theinvention for delivering radioactive emissions to body tissue;

FIG. 2 is a cross-sectional view taken along the line 2—2 in FIG. 1;

FIG. 3 is an additional embodiment of an interstitial brachytherapyapparatus of the invention having a solid radiation source;

FIG. 4 is an additional embodiment of an interstitial brachytherapyapparatus of the invention having a radiation source comprising aplurality of solid radiation particles;

FIG. 5 depicts a further embodiment of the invention wherein the innerand outer spatial volumes of the interstitial brachytherapy apparatusare non-spherical;

FIG. 6 illustrates an interstitial brachytherapy apparatus of theinvention having an expandable outer spatial volume surface; and

FIGS. 7A-D illustrate the absorbed dose versus distance into targettissue for several interstitial brachytherapy apparatus configurations.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A surgical instrument 10 for providing radiation treatment toproliferative tissue in a living patient is illustrated in FIG. 1.Surgical instrument 10 includes a tubular body member 12 having firstand second lumens 14 and 16 (FIG. 2) extending from proximal ports 18and 20 in a molded plastic hub 22 to inflation ports 24 and 26 formedthrough the side wall of the tube 12 and intersecting with the lumens 14and 16, respectively.

Affixed to the tubular body 12 proximate the distal end 28 thereof is aninner spatial volume 30 which may be defined by a generally sphericalpolymeric film wall 32. The interior of the inner volume 30 is in fluidcommunication with the inflation port 26. Surrounding inner spatialvolume 30 is an outer spatial volume 34 defined by an outer polymericfilm wall 36 that is appropriately spaced from the wall 32 of the innerspatial volume 30 when the two volumes are inflated or otherwisesupported. Outer volume 34 encompasses inflation port 24. With nolimitation intended, the distensible polymeric film walls may comprise abiocompatible, radiation resistant polymer, such as silastic rubbers,polyurethanes, polyethylene, polypropylene, polyester, or PVC.

The embodiment of FIG. 1 includes inner and outer spatial volumes 30 and34, one inside the other. The outer spatial volume 34, being the volumedefined by the space between the inner spherical wall 32 and the outerspherical wall 36, may be filled with air or, alternatively, a radiationabsorbing fluid, such as a contrast media used in angiography. The innervolume 30 is then filled with a material containing a predeterminedradionuclide, for example, I-125, I-131, Yb-169 or other source ofradiation, such as radionuclides that emit photons, beta particles,gamma radiation, or other therapeutic rays. The radioactive materialcontained within the inner chamber 32 can be a fluid made from anysolution of radionuclide(s), e.g., a solution of I-125 or I-131. Aradioactive fluid can also be produced using a slurry of a suitablefluid containing small particles of solid radionuclides, such as Au-198,Y-90. Moreover, the radionuclide(s) can be embodied in a gel. Oneradioactive material useful in the invention is Iotrex™, a sterilesingle use, non-pyrogenic solution containing sodium3-(¹²⁵I)iodo-4-hydroxybenzenesulfonate (¹²⁵I-HBS), available fromProxima Therapuetics, Inc. of Alpharetta, Ga.

As an alternative method of providing radioactive source material, suchmaterial may be coated on, chemically bonded to, or copolymerized withthe material forming inner spherical wall 32.

Where the radioactive source material is provided as a fluid or gelwithin inner spherical wall 32, it may be desirable to provide a solidouter spherical wall 36. Should inner spherical wall 32 rupture, theradioactive source material will be retained within outer spherical wall36 and will not leak into the patient. For further safety, the burststrength of inner spherical wall 32 may be designed so as to be lowerthan that of outer spherical wall 36. In this way, inner spherical wall32 will rupture under stress first, releasing its contents into thelarger combined space of the inner and outer volumes 30, 34 andreleasing any pressure built up within the inner spherical wall 32 andreducing the risk that radioactive material will spill into the patient.In the event of such a rupture, radioactive fluid could be drained fromthe apparatus through port 24 by way of lumen 14, and also from port 26by way of lumen 16.

In a further embodiment, illustrated in FIG. 3, instead of having theinner spatial volume 30 defined by a generally spherical polymeric filmwall as at 32, the catheter body member 12 may have a solid sphericalradiation emitting material 44 as the inner spatial volume 30. Forexample, radioactive micro spheres of the type available from the 3MCompany of St. Paul, Minn., may be used. This radioactive source caneither be preloaded into the catheter at the time of manufacture orloaded into the device after it has been implanted into the spaceformerly occupied by the excised tumor. The solid radiation emittingmaterial 44 can be inserted through catheter 12 on a wire 46, forexample, using an afterloader (not shown). Such a solid radioactive coreconfiguration offers an advantage in that it allows a wider range ofradionuclides than if one is limited to liquids. Solid radionuclidesthat could be used with the delivery device of the present invention arecurrently generally available as brachytherapy radiation sources. Inthis embodiment solid spherical inner spatial volume 30 is surrounded byouter spherical wall 36, defining outer spatial volume 34 between theouter spherical wall 36 and the inner spatial volume 30 with the outerspatial volume 34 occupied by a radioactive ray absorbent material, suchas air, water or a contrast material.

In a further embodiment, illustrated in FIG. 4, inner spatial volume 30,instead of comprising a single solid sphere, may comprise a plurality ofradiation emitting particles 44 strategically placed within the innerspatial volume 30 so as to radiate in all directions with asubstantially equal intensity. This plurality of radiation emittingparticles 44 can be mounted on the distal ends of a plurality of wires46 that are routed through the catheter body 12 and exit a plurality ofports formed through the wall of the catheter body and reaching thelumen. This arrangement allows the exact positioning of the individualradiation sources 44 to be positioned so as to generate a desiredresultant profile.

As illustrated in FIG. 5, it is not essential to the invention that thevolumes 30 and 34 have spherical walls, so long as the resultant dosingprofile is consistent with the shape of the outer volume 34. That is,the absorbed dose within the target tissue at points equidistant fromthe surface 36 of the outer spatial volume 34 should be substantiallyuniform in substantially every direction. Put another way, the threedimensional isodose profiles generated by the radiation source should besubstantially similar in shape to the outer spatial volume 34. Where theinner and outer spatial volumes are created by inflatable membranes andone of the volumes contains a fluid radiation source, this can beachieved by ensuring that the spacing between the wall of the innervolume and the wall of the outer volume remain generally constant. Ineither the concentric spherical embodiment of FIG. 1 or thenon-spherical configuration of FIG. 5, this result can be achieved bycareful placement of precision blown or molded polymer partitions or byusing compressible foams or mechanical spacers in the form of websjoining the inner wall 32 to the outer wall 36. The desired isodoseprofiles conforming to the shape of the outer spatial volume 34 can alsobe obtained, for example, by strategic placement of a plurality ofradioactive particle sources within the inner spatial volume 30. Wherethe apparatus of the invention is deployed in soft tissue, it may alsobe important for the surface 36 of the outer spatial volume 34 to besufficiently firm so as to force the target tissue to take on the shapeof the surface 36 so that the desired relationship between the isodoseprofiles and the target tissue is achieved.

When used in an interstitial application, the surface of the outerspatial volume 34 must establish a relationship between the innerspatial volume 30 and the target tissue so as to achieve theaforementioned isodose profile, however, the surface of the outer volumeneed not be a solid material. For example, as illustrated in FIG. 6, thesurface of the outer volume 34 could be an expandable cage 48 formedfrom a shape memory metal, such as nitinol, or a suitable plastic, suchas an expandable polyethylene cage. Such a cage can be formed in thedesired shape to conform to a particular isodose profile, then becontracted for delivery to the target site in vivo, then expanded tocause the tissue surrounding the surgically resected region to take theappropriate shape. The size of the outer spatial volume 34 generallywill correspond approximately to the amount of tissue resected, or beslightly larger, allowing the expandable surface of the outer spatialvolume to urge tissue on the surface of the resected region into theappropriate shape to promote an even dose distribution around the outerspatial volume in the target tissue. In typical applications, the outerspatial volume has a diameter of approximately 2 to 4 centimeters. Inthese same applications, where the radiation source is provided as afluid within an inner balloon, the inner balloon generally has adiameter of approximately 0.5 to 3 centimeters.

FIGS. 7A-D illustrate the ability of an interstitial brachytherapyapparatus of the invention to deliver a minimum prescribed dose withintarget tissue while avoiding necrosis inducing radiation “hot spots” intissue proximate to the apparatus. FIG. 7A illustrates an interstitialbrachytherapy apparatus (device A) such as those employed in U.S. Pat.No. 5,429,582, having a single spatial volume 50 filled with aradioactive material in solution. FIG. 7B illustrates an interstitialbrachytherapy apparatus (device B) of the invention having a first,inner spatial volume 30 filled with a radioactive material in solutionand defined by membrane 32, and a second, outer spatial volume 34defined by membrane 36 that is substantially evenly spaced apart frommembrane 32 in substantially three dimensions. FIG. 7C illustrates anadditional interstitial brachytherapy apparatus (device C) of theinvention having a solid, spherical radiation source 44 as the innerspatial volume and a spherical outer spatial volume 34 defined bymembrane 36.

Each of the devices illustrated in FIGS. 7A-C can be configured todeliver a substantially uniform dose at a given distance into the targettissue from the surface of the outer spatial volume 34 (or from singlespatial volume 50 for device A) and to deliver a minimum prescribed dosewithin a given prescribed depth range into the tissue from the surfaceof the outer spatial volume 34. However, the different devices providevery different dose profiles as a function of distance from the surfaceof the outer volume as illustrated in FIG. 7D. FIG. 7D plots theabsorbed dose at a given distance into the target tissue from thesurface of the outer spatial volume 34 for each of the devices A, B, andC.

Each device can deliver a minimum prescribed dose 52 at a given distancefrom the surface of the outer spatial volume. For example, device A canreadily be configured to provide a dose in a therapeutic range, saybetween 40 to 60 Gray, at a distance between 0.5 and 1.0 cm from theouter spatial volume for an outer spatial volume having a diameter of4.0 cm and being in contact with the resection cavity wall. In a typicalembodiment, the radioactive source material ranges from approximately150 to 450 mCi in activity and encompasses most of the target treatmentarea with a 0.4 to 0.6 Gray/hour isodose contour. At this treatmentrate, treatment may be completed in approximately 3 to 7 days, or morecommonly, in approximately 3 to 5 days.

In order to reach the minimum prescribed dosage at this distance,however, device A must provide a dose proximate to the surface of theouter spatial volume that is substantially larger than the minimumprescribed dose. For the 4.0 cm diameter outer spatial volume example,the absorbed dosage would be approximately 131 Gray at the outer spatialvolume surface. Ideally, radiation therapy should make use the inherentdifference in radiosensitivity between the tumor and the adjacent normaltissues to destroy cancerous tissue while causing minimal disruption tosurrounding normal tissues. At high doses of radiation, however, thepercentage of exposed cells that survive treatment decreases withfirst-order kinetics in proportion to increasing radiation dose. Withincreasing cell death comes increasing risk of necrosis or tissue deathin healthy tissue that is treated with a high dose of radiation.Accordingly, it is desirable to keep the maximum radiation dosedelivered by the brachytherapy apparatus as low as possible while stilldelivering the desired therapeutic dose to the desired range of tissue.

Comparing the plots A, B, and C, the absorbed dose profile in the spacebetween the 2 cm site and the surface of the outer spatial volume forthe devices of the invention is maintained in a much narrower range,preventing over-treatment of body tissue at or close to the surface ofthe outer volume of the device. Because devices B and C provide an outerspatial volume 34 between the radioactive source and the target tissue,these devices can use hotter radiation sources to reach the minimumprescribed dosage, but take advantage of the distance between theradioactive source and the target tissue provided by the outer spatialvolume 34 to reduce or eliminate hot spots in the target tissue.

Returning to the 4.0 cm diameter outer spatial volume example, if theradiation source is contained within an inner spatial volume, say asolid radioactive sphere such as device C, the absorbed dose profilebecomes much different. If the radiation source is configured to providethe same 60 Gray dose at 0.5 cm into the target tissue, the absorbeddose at the outer spatial volume surface is only 94 Gray—a significantdecrease from the 131 Gray dose for a type A device. In addition, thetreatment range for the type C device will be extended under thesecircumstance as compared to the type A device, delivering a 40 Gray dosebeyond 1.0 cm into the target tissue and delivering approximately doublethe dose at 3.0 cm into the target tissue. In one embodiment, the innerand outer spatial volumes are configured to control the absorbed dose atthe outer spatial volume surface so that the absorbed dose is no greaterthan about 100 Gray while providing a therapeutic absorbed dose into thetarget tissue at the desired range. The capability of the apparatus ofthe invention to deliver absorbed doses deeper into the target tissuethan prior interstitial brachytherapy devices while controlling the dosein proximity to the apparatus to reduce or eliminate the risk of healthytissue necrosis allows for the use of brachytherapy in a greater numberof cases.

The interstitial brachytherapy apparatus of the invention can be used inthe treatment of a variety of malignant tumors, and is especially usefulfor in the treatment of brain and breast tumors.

Many breast cancer patients are candidates for breast conservationsurgery, also known as lumpectomy, a procedure that is generallyperformed on early stage, smaller tumors. Breast conservation surgery istypically followed by postoperative radiation therapy. Studies reportthat 80% of breast cancer recurrences after conservation surgery occurnear the original tumor site, strongly suggesting that a tumor bed“boost” of local radiation to administer a strong direct dose may beeffective in killing any remaining cancer and preventing recurrence atthe original site. Numerous studies and clinical trials have establishedequivalence of survival for appropriate patients treated withconservation surgery plus radiation therapy compared to mastectomy.

Surgery and radiation therapy are the standard treatments for malignantsolid brain tumors. The goal of surgery is to remove as much of thetumor as possible without damaging vital brain tissue. The ability toremove the entire malignant tumor is limited by its tendency toinfiltrate adjacent normal tissue. Partial removal reduces the amount oftumor to be treated by radiation therapy and, under some circumstances,helps to relieve symptoms by reducing pressure on the brain.

A method according to the invention for treating these and othermalignancies begins by surgical resection of a tumor site to remove atleast a portion of the cancerous tumor and create a resection cavity.Following tumor resection, but prior to closing the surgical site, thesurgeon intra-operatively places an interstitial brachytherapy catheterapparatus, having an inner spatial volume and an outer spatial volume asdescribed above but without having the radioactive source materialloaded, into the tumor resection cavity. Once the patient hassufficiently recovered from the surgery, the interstitial brachytherapycatheter is loaded with a radiation source. The radioactive sourcedwells in the catheter until the prescribed dose of radiotherapy isdelivered, typically for approximately a week or less. The radiationsource is then retrieved and the catheter is removed. The radiationtreatment may end upon removal of the brachytherapy apparatus, or thebrachytherapy may be supplemented by further doses of radiation suppliedexternally.

It will be understood that the foregoing is only illustrative of theprinciples of the invention, and that various modifications can be madeby those skilled in the art without departing from the scope and spiritof the invention. All references cited herein are expressly incorporatedby reference in their entirety.

What is claimed is:
 1. An interstitial brachytherapy apparatus fordelivering radioactive emissions to an internal body locationcomprising: (a) a catheter body member having a proximal end and distalend; (b) an inner spatial volume disposed proximate to the distal end ofthe catheter body member; (c) an outer spatial volume defined by anexpandable surface element disposed proximate to the distal end of thebody member in a surrounding relation to the inner spatial volume; and(d) a radiation source disposed in the inner spatial volume andgenerating a three-dimensional isodose profile that is substantiallysimilar in shape to the expandable surface element.
 2. The apparatus ofclaim 1, wherein the inner and outer spatial volumes are configured toprovide a minimum prescribed absorbed dose for delivering therapeuticeffects to a target tissue, the target tissue being defined between theouter spatial volume expandable surface and a minimum distance outwardfrom the outer spatial volume expandable surface, the apparatusproviding a controlled dose at the outer spatial volume expandablesurface to reduce or prevent necrosis in healthy tissue proximate to theexpandable surface.
 3. The apparatus of claim 2, wherein a predeterminedspacing is provided between said inner spatial volume and the expandablesurface element.
 4. The apparatus of claim 3, wherein the expandablesurface element is adapted to contact tissue surrounding a resectedcavity and adapted to conform the tissue to the desired shape of theexpandable surface element.
 5. The apparatus of claim 2, wherein theminimum prescribed absorbed dose is 40 Gray at a distance of at leastone centimeter from the expandable surface element.
 6. The apparatus ofclaim 5, wherein the dose rate in at least a portion of the targettissue is between about 0.4 and 0.6 Gray/hour.
 7. The apparatus of claim5, wherein the maximum absorbed dose delivered to the target tissue isless than 100 Gray.
 8. The apparatus of claim 2, wherein the outerspatial volume has a diameter between about two and four centimeters. 9.The apparatus of claim 2, wherein the inner spatial volume is an innerclosed, distensible chamber defined by a further radiation transparentwall.
 10. The apparatus of claim 9, wherein the radioactive source is ina fluid form.
 11. The apparatus of claim 10, wherein the expandablesurface element is a solid distensible surface and the outer spatialvolume is a closed, distensible chamber and the expandable surfaceelement is a radiation transparent wall.
 12. The apparatus of claim 11,wherein a burst strength of the distensible chamber defining the outerspatial volume is greater than a burst strength of the chamber definingthe inner spatial volume.
 13. The apparatus of claim 1, wherein theexpandable surface element is an expandable cage.
 14. The apparatus ofclaim 13, wherein the expandable cage comprises a shape memory material.15. The apparatus of claim 14, wherein the expandable cage comprisesnitinol.
 16. The apparatus of claim 1, wherein the radiation source is asolid radiation source.
 17. The apparatus of claim 1, wherein theradiation source is a plurality of solid radiation sources arranged toprovide an isodose profile having a shape substantially similar to theshape of the outer spatial volume.
 18. The apparatus of claim 2, whereinthe prescribed absorbed dose is delivered to the target tissue insubstantially three dimensions.
 19. A method for treating aproliferating tissue disease using interstitial brachytherapy at aninternal body location comprising: (a) surgically creating access to theproliferating tissue in a patient; (b) surgically resecting at least aportion of the proliferating tissue to create a resection cavity withinbody tissue; (c) providing an interstitial brachytherapy apparatus fordelivering radioactive emissions comprising: (i) a catheter body memberhaving a proximal end and distal end; (ii) an inner spatial volumedisposed proximate to the distal end of the catheter body member; (iii)an outer spatial volume defined by an expandable surface elementdisposed proximate to the distal end of the body member in a surroundingrelation to the inner spatial volume; and (iv) a radiation sourcedisposed in the inner spatial volume and generating a three-dimensionalisodose profile that is substantially similar in shape to the expandablesurface element; (d) intraoperatively placing the interstitialbrachytherapy apparatus into the resection cavity until a prescribedabsorbed dose has been delivered to tissue surrounding the apparatus;and (e) removing the interstitial brachytherapy apparatus.
 20. Themethod of claim 19, further including placing the radioactive sourceinto the interstitial brachytherapy apparatus after the step of placingthe apparatus into the tumor resection cavity.
 21. The method of claim19, further including removing the radioactive source from theinterstitial brachytherapy apparatus before the step of removing theapparatus.
 22. The method of claim 19, wherein the proliferating tissueis a patient's brain.
 23. The method of claim 19, wherein theproliferating tissue is a patient's breast.
 24. The method of claim 19,further including configuring the inner and outer spatial volumes toprovide a minimum prescribed absorbed dose for delivering therapeuticeffects to a target tissue, the target tissue being defined between theouter spatial volume expandable surface and a minimum distance outwardfrom the outer spatial volume expandable surface, the apparatusproviding a controlled dose at the outer spatial volume expandablesurface to reduce or prevent necrosis in healthy tissue proximate to theexpandable surface.
 25. The method of claim 24, further includingproviding a predetermined spacing between said inner spatial volume andthe expandable surface element.
 26. The method of claim 25, wherein theexpandable surface element is adapted to contact tissue surrounding aresected cavity and adapted to conform the tissue to the desired shapeof the expandable surface element.
 27. The method of claim 24, whereinthe minimum prescribed absorbed dose is 40 Gray at a distance of atleast one centimeter from the expandable surface element.
 28. The methodof claim 27, wherein the dose rate in at least a portion of the targettissue is between about 0.4 and 0.6 Gray/hour.
 29. The method of claim27, wherein the maximum absorbed dose delivered to the target tissue isless than 100 Gray.
 30. The method of claim 24, wherein the outerspatial volume has a diameter between about two and four centimeters.31. The method of claim 24, wherein the step of configuring the innerand outer spatial volumes includes expanding the inner and outer spatialvolumes.
 32. A method for treating a proliferating tissue disease usinginterstitial brachytherapy at an internal body location comprising: (a)surgically creating access to the proliferating tissue in a patient; (b)surgically resecting at least a portion of the proliferating tissue tocreate a resection cavity within body tissue; (c) providing aninterstitial brachytherapy apparatus for delivering radioactiveemissions comprising: (i) a catheter body member having a proximal endand distal end; (ii) an inner spatial volume disposed proximate to thedistal end of the catheter body member; (iii) an outer spatial volumedefined by an expandable surface element disposed proximate to thedistal end of the body member in a surrounding relation to the innerspatial volume; and (iv) a radiation source disposed in the innerspatial volume; (d) intraoperatively placing the interstitialbrachytherapy apparatus into the resection cavity; (e) configuring theinner and outer spatial volumes to provide a minimum prescribed absorbeddose for delivering therapeutic effects to a target tissue, the targettissue being defined between the outer spatial volume expandable surfaceand a minimum distance outward from the outer spatial volume expandablesurface, the apparatus providing a controlled dose at the outer spatialvolume expandable surface to reduce or prevent necrosis in healthytissue proximate to the expandable surface; and (f) removing theinterstitial brachytherapy apparatus.
 33. The method of claim 32,wherein the step of configuring the inner and outer spatial volumesincludes expanding the inner and outer spatial volumes.
 34. A method fortreating a proliferating tissue disease using interstitial brachytherapyat an internal body location comprising: (a) surgically creating accessto the proliferating tissue in a patient; (b) surgically resecting atleast a portion of the proliferating tissue to create a resection cavitywithin body tissue; (c) providing an interstitial brachytherapyapparatus for delivering radioactive emissions comprising: (i) acatheter body member having a proximal end and distal end; (ii) an innerspatial volume disposed proximate to the distal end of the catheter bodymember; (iii) an outer spatial volume defined by an expandable surfaceelement disposed proximate to the distal end of the body member in asurrounding relation to the inner spatial volume; and (iv) a radiationsource disposed in the inner spatial volume; (d) intraoperativelyplacing the interstitial brachytherapy apparatus into the resectioncavity; (e) adapting the expandable surface element to contact tissuesurrounding the resection cavity to conform the tissue to the desiredshape of the expandable surface element; (f) delivering a prescribedabsorbed dose to tissue surrounding the apparatus; and (g) removing theinterstitial brachytherapy apparatus.
 35. The method of claim 34,wherein the step of adapting the expandable surface element includesexpanding the outer surface volume.
 36. An interstitial brachytherapyapparatus for delivering radioactive emissions to an internal bodylocation comprising: (a) a catheter body member having a proximal endand distal end; (b) an inner spatial volume disposed proximate to thedistal end of the catheter body member; (c) an outer spatial volumedefined by an expandable surface element disposed proximate to thedistal end of the body member in a surrounding relation to the innerspatial volume; and (d) a radiation source disposed in the inner spatialvolume; wherein the inner and outer spatial volumes are configured toprovide a minimum prescribed absorbed dose for delivering therapeuticeffects to a target tissue, the target tissue being defined between theouter spatial volume expandable surface and a minimum distance outwardfrom the outer spatial volume expandable surface, the apparatusproviding a controlled dose at the outer spatial volume expandablesurface to reduce or prevent necrosis in healthy tissue proximate to theexpandable surface.